Brachial plexus injury developing after axillary thoracotomy is an uncommon complication. But if it occurs, it may cause annoying events. We recently experienced 2 patients who developed brachial plexus injury after wedge resection by axillary thoracotomy . The first patient was a 22 year-old man with right spontaneous pneumothorax . After wedge resection of the right upper lung by axillary thoracotomy, he complained total paralysis of the right arm. An electromyogram was obtained at 7 days after operation, with the confirmation of brachial plexus injury. He was discharged at 22days after operation and brachial plexus injury was completely recovered 4 months after discharge. The second patient was a 17 year-old man with recurrent right pneumothorax. He underwent wedge resection of the right upper lung by axillary thoracotomy. Electromyogram confirmed the diagnosis of brachial plexus injury in the immediate postoperative period. He was discharged at 15 days after operation and brachial plexus injury was recovered 2months after discharge.Brachial plexus injury after axillary thoracotomy is caused by stretching around the clavicle and tendon of pectoralis minor by fixation of the abducted arm to the frame. Thus, when we perform wedge resection by axillary thoracotomy, we must avoid over-stretching of the brachial plexus in positioning. If brachial plexus injury develops, immediate attention and management with close rapport are important to avoid possible medicolegal problems.